Generally, airbag modules for vehicles include an airbag module for a driver's seat that is installed in a steering wheel, and an airbag module for a passenger seat that is installed in an instrument panel ahead of the passenger seat.
Typically, taking the appearance into account, the airbag modules are installed to be covered with airbag doors. A cutting line such as a line groove is formed in an inner or outer surface of such an airbag door.
Thus, when an airbag of the airbag module is deployed, the airbag door is torn along the cutting line and is opened in both directions.
However, there is a problem in that, when the airbag door is torn and opened, fragments or the like are scattered from portions of the airbag door that are adjacent to the cutting line and may inflict an injury on a user.
Furthermore, because a separate hinge structure is not used on a rotation center point of the airbag door, the airbag door may not be smoothly rotated or opened outward. If the airbag door is not completely opened, the deployment of the airbag may be impeded by the airbag door.
In an effort to overcome the above-mentioned problems, a structure in which a fabric sheet formed by weaving warp yarns and weft yarns is attached to an inner surface of an airbag door to control deployment of an airbag door in multi-steps was proposed in U.S. Pat. No. 8,348,303 (“303 patent”).
In more detail, the fabric sheet introduced in the '303 patent is formed by alternately arranging stop warp yarns for supporting a load and base warp yarns parallel with each other in a direction in which force is applied when the airbag explodes, and weaving weft yarns with the warp yarns in a grid shape. The stop warp yarns for supporting the load are longer than the base warp yarns.
In this regard, opposite ends of the stop warp yarns for supporting the load overlap with each other in a zigzag form and thus function as hinges of the airbag door.
That is, when the airbag door opens, the base warp yarns are snapped, but the longer stop warp yarns for support the load function as hinges for rotation of the airbag door without being snapped.
However, in the configuration of the fabric sheet introduced in the '303 patent, the stop warp yarns for supporting the load may be snapped by the pressure of explosion of the airbag. If the stop warp yarns are snapped, they cannot function as the hinges of the airbag door, whereby the airbag door may be separated from the original position thereof and scattered outward.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.